<input [formControl]="username">
<form [formGroup]="formModel" (submit)="onsubmit()">
  <input formControlName="usernames">
  <div formGroupName="dateRange">
    起始日期：<input type="date" formControlName="from">
    截至日期：<input type="date" formControlName="to">
  </div>
  <div>
    <ul formArrayName="emails">
      <li *ngFor="let email of this.formModel.get('emails').controls; let i=index;">
        <input type="text" [formControlName]="i">
      </li>
    </ul>
    <button type="submit" (click)="addEmail()">增加Email</button>
  </div>
  <div>
    <button type="submit">保存</button>
  </div>
</form>
